1. Field of the Invention
The present invention relates to compositions for use as adhesion promoters on polyolefin substrates and to a method of applying such compositions to the polyolefin substrate. More particularly, the present invention relates to compositions containing chlorinated polyolefins for use as adhesion promoters and to a method of applying such compositions to polyolefin substrates.
2. Brief Description of the Prior Art
Polyolefins such as ethylene and propylene as well as copolymers thereof are being used in increasing amounts in the fabrication of automobile bodies and trim such as front end fascia and filler panels located between the bumper and the chassis. These materials are light weight and have excellent impact resistance. They can withstand low speed collisions much better than metal counterparts. However, to be aesthetically acceptable, the polyolefin must be painted to match the paint on the rest of the automobile. Because of the low surface tension of polyolefins, it is very difficult to adhere paint directly to the surface of the polyolefin.
It is known in the industry that the adhesion of a paint layer to a polyolefin substrate can be improved if the substrate is first treated with an adhesion promoter. Typical adhesion promoters are solutions of chlorinated polyolefins which when applied as a coating to the polyolefin substrate act as a tie layer between the polyolefin and the subsequently applied paint. However, if the adhesion promoter is not applied uniformly to the polyolefin substrate, the adhesion of the subsequently applied coating will fail.
It is an object of the present invention to provide a detectable adhesion promoting composition, that is, one which when applied to the polyolefin substrate can be determined if it has been applied uniformly to the substrate.